1. Field
This disclosure relates generally to an electronic assembly and, more specifically to techniques for installing a heatsink in an electronic assembly.
2. Related Art
In a heatsink on electronic module (or integrated circuit (IC)) application, it has been observed that loading at corners of the heatsink has induced a bow in a base of the heatsink. This is due, at least in part, to loads being applied at some distance from an opposing surface which has caused a base of the heatsink to bend, which affects a planarity between the module and a pedestal of the heatsink. When the corners of a heatsink are loaded, the heatsink has bent concave down, which has increased a gap between a center of the module and the heatsink. This has also generally exposed corners of the module to higher pressure. In a typical electronic assembly there are four (one at each corner) loading mechanisms per heatsink. To gradually increase a heatsink load, fasteners at the corners of the heatsink have typically been cross-tightened during installation of the heatsink in the electronic assembly. While increasing corner loads on a heatsink incrementally provides relatively even heatsink loads, the heatsink loads are still concentrated at each corner of the heatsink as the fasteners are actuated, irrespective of how small the increment is on each of the fasteners. In a typical electronic assembly, load concentration has required special consideration to ensure that loads, which have acted on corners of an electronic module, have not cracked the corners of the module.
One approach for addressing the incremental loading problem has applied a central load to a top of a heatsink using a fixture and then actuated corner loading mechanisms of the heatsink. After the corner load mechanisms were tightened to their stops, the fixture was then removed. While applying a fixture load to a center of a heatsink has resulted in a relatively flat profile at a base of the heatsink (due to the applied load being directly over the opposing force (module)) during installation of the heatsink, applying a load to the center of the heatsink with a fixture has caused an employed thermal interface material (TIM) to be compressed to a profile that is representative of a centrally loaded system. Unfortunately, when the load is removed from the fixture, the heatsink has deflected to a bowed profile that has corresponded to a corner loaded heatsink. That is, a center of the heatsink has bowed up and away from the TIM (which was compressed to a fixed height when the fixture load was applied) which has lead to air entrapment between the heatsink pedestal and the TIM, e.g., thermal grease. Unfortunately, air bubbles between a TIM and a heatsink pedestal or module may lead to premature failure of the module due to the inability of the TIM to adequately transfer heat from the module to the heatsink.